Background and Objective: We examined differences in blood pressure (BP) levels between first-generation immigrants and native-born in a large population of adult residents in Northeast Italy, and investigated the role of lifestyle behaviours, body mass index (BMI), and education as potentially modifiable mediating factors. Methods: We included 20-69 years-old participant of a Health Surveillance Program of the Veneto Region (n=37,710). Immigrant status was defined by being born in a high migratory pressure country (HMPC) and subdivided by geographical macro-areas. Hypertension was defined as abnormal measured BP values, self-reported diagnosis, or anti-hypertensive drug use. We used t-tests and chi-square tests to assess the association between migrant status and potential mediating factors, and generalized linear models to test the association of each covariate with the outcomes. A multiple mediation analysis including all covariates that satisfied the previous conditions was performed, applying the counterfactual framework by Yu. Results: Of the 37,380 subjects included in the analysis, 8.7% were born in a HMPC. BMI, education, alcohol, sweets and meat consumption were included in the models as potential mediators. A tiny advantage in Systolic BP levels was seen for immigrants compared to natives (β=-0.71, 95%CI:-1.30;-0.10). The direct effect (net of the included covariates) was a reduction of 1.62 mmHg (95%CI:-2.25;-0.98), among immigrants compared to natives. BMI played the highest suppressive role of this health advantage (β=1.14, 95%CI:0.99;1.35), followed by education. The distribution of alcohol consumption instead increased the health advantage for immigrants. The BMI suppressing effect was particularly evident among females and North African immigrants compared to natives. Similar Results were seen for hypertension rates. Conclusions: Although causation cannot be proven in this cross-sectional study, our findings highlight the important suppression role played by BMI in the differences of BP levels by migrant status, indicating a possible target to preserve the health advantage of immigrants.